On Wednesday 23 August 2006 10:37, aurora wrote: > ISP's SMTP server which then hits the customers SMTP/POP server. In most > cases, your SMTP server will just find a direct route to the destination > server and only the sending server and receiving server will be involved > without a server being "in the middle", no?
Eh - sort of. Your SMTP relayhosts/smarthosts to your ISP. The ISP server will usually do an MX query for the destination domain of the e-mail, and deliver to that server. That server is not necessarily the post-box server - it may have to feed the mail to another server, and so on. > Is it not classed as a form of open relaying, even though there is a form > of authentication (IP check) on it? Both our external IP and the ISP's > email IP are not listed on any blacklist (checked with dnsstuff.com). No, smarthosting isn't open relaying. While dnsstuff.com may not list them, I'd still ask the customer to get the rules that scored the e-mail high enough for quarantine. Only by seeing the rule names will you be able to determine what characteristics of the e-mail are triggering the quarantine.
